The overall objective is a detailed evaluation of the pharmacokinetics (absorption, distribution, biotransformation and excretion) of naltrexone and 1-acetylmethadol in animals and man, with particular reference to the accumulation of these drugs in the reproductive organs, their excretion in semen, disposition in the lung and in the isolated perfused rat liver. The protocol was to develop analytical methodology in the course of the animal studies and apply the methods to further studies in man, including studies on the effect of 1-alpha acetylmethadol on respiratory function.